The invention relates to a drying agent box for drying compressed air, comprising a housing having at least one inlet and at least one outlet, and a body of drying agent contained in said housing interposed in a flow path between the inlet and the outlet.
Published German Patent Application No. DE 197 04 178 discloses a drying agent box for an air dryer, which has an inlet and an outlet. The inlet is releasably joined to a passage in the interior of the housing. The passage adjoins a perforated plate which has inlet and outlet openings. On this perforated plate a pipe section opposite the passage is formed which affects the direction of flow of the air. A container filled with granular drying agent is applied to the perforated plate, and a foam material layer extends over the drying agent. A cover, which is screwed into the housing, serves to affix the container full of drying agent to the perforated plate. The drying agent can be replaced by removing the container from the air dryer.
In view of the loose filling of drying agent, however, no precise filling of the container is possible, so that there is a danger that voids may form between the granular drying agent, which shrink in size when in operation, and thus no more compression prevails in the drying agent. Another disadvantage of this embodiment is the mounting of the container filled with drying agent onto the perforated plate. In this case the pipe section must extend into the drying agent, which presents problems in an optimally filled container. Furthermore, in this embodiment of an air dryer components are necessary for holding and compressing the drying agent, and this involves an expenditure of money and material, and also the weight of the parts is increased.
It is therefore the object of the invention to provide a drying agent box which has a simple structure.
It is also an object of the invention to provide a drying agent box which is easy to install and to maintain.
Another object of the invention is to provide a drying agent box which is light weight and can be manufactured at reasonable cost.
These and other objects are achieved in accordance with the invention by providing a drying agent box for drying compressed air, comprising a housing having at least one inlet and at least one outlet, and a body of drying agent contained in said housing interposed in a flow path between the inlet and the outlet, wherein the drying agent body has a stable shape.
The drying agent box of the invention is advantageously suited to remove moisture from air, at the same time assuring ease of installation and maintenance.
The drying agent box comprises a housing with a container and a flange. The container is sealingly joined to the flange. This can be accomplished by screwing or snapping the parts together. If desired, a gasket may be inserted between the housing and flange to seal them to each other. The housing has an inlet and an outlet. The inlet is sealingly joined to a one-piece drying agent body which is made, for example, by sintering with pores, or by casting with built-in channels so that no leakage occurs between inlet and outlet. The drying agent body has a stable shape and can be used as an independent unit in the container. Thus granule containers and their fastening means can be dispensed with.
It is advantageous to insert an oil separator between the inlet and the drying agent body. In such a case, variations are possible in the manner of installation or assembly between the flange and the funnel, which define a path of flow for the air, or variants of installation in the gap between the container and the drying agent body. In this way oil can be removed from oily air before it comes in contact with the drying agent body. This lengthens the useful life of the drying agent body, since oil no longer clogs the pores which absorb the moisture.
In accordance with another embodiment of the invention the drying agent body is divided into segments which contain channels for carrying the flow. These channels carry the air from the inlet through the drying agent body. After passing once through the drying agent body the air can reach the outlet.
In other variants, after the air has left the drying agent body it is turned around in the container and flows again in the opposite direction through the drying agent body toward the outlet. The repeated passage of the air through the drying agent body achieves a greater degree of dryness.
One specific embodiment of the invention has a gap between the drying agent body and the housing. If the air to be dried is fed through the gap, the air can be pre-dried at the circumferential surface of the drying agent body before it enters the drying agent body and flows toward the outlet.
Another embodiment of the invention provides for sealing the drying agent body to the housing. Thus any cross flow carrying insufficiently dried air to the outlet is prevented. In this case the sealing can be accomplished by means of a jacket. This jacket can also have a vibration damping action, so that the drying agent is not exposed to any direct vibration. The jacket can have different configurations. In one variant, a jacket of an elastomer is applied around the drying agent body, clinging to it tightly, and absorbs slight, weak or strong shocks depending on the jacket""s thickness. Embodiments with textured jackets are conceivable, which can have textures on the inside or outside. For better utilization of space, in this variant a gap between the drying agent body and the housing can be omitted, so that a better support of the drying agent body is additionally achieved.
An advantageous embodiment of the inventive concept is a modular form of the drying agent body. In this case, the drying agent body is composed of at least two drying agent modules, which can have air ducts in them, though this is not absolutely necessary. A combination of directional-flow drying agent modules with nondirectional-flow drying agent modules is another possible variant. With a modular construction, the drying of the air may be improved, since when it enters a directional-flow drying agent module it still has a turbulent flow which nevertheless changes after a certain distance to a linear flow. In the case of linear air flow only the marginal areas are thoroughly dried by contact with the dir duct, and in the center of the air flow an isolated, poorly dried area forms. If a plurality of drying agent modules are arranged in succession, the linearized air exits from one air duct and must enter another air duct, while the well-dried air mixes with the poorly dried air and a turbulent flow of air is again achieved.
The drying agent modules can be sealingly fastened, for example, to ribs or other projections on the housing.
In accordance with another embodiment of the invention, connecting elements are provided, which join the individual drying agent modules sealingly together. These connecting elements can be of annular shape and extend around the circumference of the drying agent modules. The connecting pieces space the drying agent modules sufficiently apart to achieve the desired turbulence. In other embodiments the connecting pieces have a separating partition which is air-permeable. The permeability of the partition can be created by providing it with slits, holes or other openings. Another embodiment of the invention involves the use of one connecting element in which all of the drying agent modules are integrated. The connecting elements can be made of metal and adhesively bonded or cemented sealingly to the drying agent modules, or they can be fastened mechanically to the drying agent bodies with the use of a gasket. Furthermore, it is possible to make the connecting elements of synthetic resin materials, especially elastomers. In selecting the material for the individual connecting pieces, combinations of metal and synthetic resin may also be chosen.
It is advantageous to bias the drying agent bodies within the housing with a resilient element, such as a spring, which urges the drying agent body against the housing. This will prevent the drying agent body from vibrating in the housing and thereby destroying itself. The spring can be in the form of a spiral or leaf spring. Other types of resilient element are also possible, provided they can serve the purpose of resiliently urging the drying agent body against the housing due to their material properties, such as compressibility in the case of foams, for example, their geometry, especially a wavy shape, or mechanical operation.
Furthermore, the drying agent body can be adhesively bonded or cemented into the housing. This prevents movements of the drying agent body relative to the housing.
Another possible way of fastening the drying agent body in the housing is to provide the drying agent body and/or the housing with fastening points. In a first embodiment, only the drying agent body has fastening points which rest against the housing but the housing has no fastening points formed on it. A second variant provides fastening points formed only on the housing, and the drying agent body is supported thereon. And a third variant has fastening points both on the drying agent body and on the housing, which together provide for the fastening of the drying agent body in the housing. The fastening of the drying agent body to the housing can be achieved, e.g., by clips, screws or a bayonet connector. Furthermore, the drying agent body can be clamped within the housing without any special holding means.